Help 2001 G16

[meheron]

I have a 2001 G16 bought 3 years ago. It has always had a speed issue, it runs around 10 MPH and seems to run slower at other times. When there is 4 people on it, it runs even slower and going up the slightest incline it slows down to a crawl. I replaced all batteries 2 years ago. When you depress the pedal it seems like it runs at the same speed all the time.I would think there should be some variable when you depress the pedal. Where can I start to trouble shoot this problem. I cannot find a reputable place in my area to repair this cart, I bought it from a dealer and complained from week one, he blew me off and I don't want to take it back to him. Any help would be great. Thanks